The mission of the Gene Targeting and Transgenic Shared Resource (GeTT) is to ensure that Roswell Park CCSG members have access to state-of-the-art transgenic mouse technologies, methods and animal models. With the development of contemporary mammalian genome manipulation technologies, genetically engineered mice have become a source of new cancer models that have helped elucidate pathways contributing to tumor development and progression. GeTT has generated over 1,000 novel genetically engineered mouse lines for CCSG program members. The recent introduction of CRISPR/Cas9 genome editing technologies has drastically improved the efficiency of generating new mouse models, and enabled some critical new research by Roswell Park investigators that would not have been otherwise possible. In the reporting period (2013- 2017), the GeTT served a total of 47 Roswell users, of which 42 (89%) were CCSG members. Typically, GeTT charges its CCSG members ~one-third of what commercial companies would charge to create genetically engineered mice. The Resource Director and Co-Director provide guidance to investigators from the earliest planning stages of the project when constructs are designed to advanced stages of the project during phenotype analysis. Resource technicians perform the specialized ES cell and embryo manipulation methods to generate the genetically engineered mice. Projects requiring the development of transgenic mouse models are becoming increasingly relevant to validate findings from in vitro studies and from high-throughput clinical- based datasets. The Specific Aims of the GeTT are: 1) To ensure that Roswell Park CCSG members, have access to state-of-the-art transgenic methods, technologies, and mouse models; 2) To serve as a ?one-stop? Shared Resource for consultation, education, training and expert support related to genetic engineering of mouse models; 3) To work synergistically with other shared resources at Roswell Park to provide the optimized research environment for CCSG members. The GeTT has significant expertise in providing all the necessary technologies and services to achieve the objectives of the Aims. The GeTT future plan is to increase the number of CCSG members utilizing the GeTT by optimizing several new CRISPR-based genome-editing techniques. GeTT is currently developing new techniques such as Easi-CRISPR and GONAD (Gonadal oviductal transfer of Nucleic Acid Delivery). In addition GeTT has recently developed a service that offers mouse colony management to CCSG member labs who do not have previous experience in complex mouse breeding for cohort analysis.